Sikome Lake has been closed to the public as emergency crews continue to search for a man who went into the water Monday afternoon.
Police say they received a call about a child in the water at 3:56 p.m. MT Monday.
According to the Calgary Fire Department, four people and two children were on an inflatable water craft when three adults and one infant entered the water for reasons unknown at this time.
Witnesses on the beach were able to rescue two adults and the infant.
However, the 29-year-old man is still missing.
Members of the fire department's aquatic team are continuing their search for him using spotters, line tenders, divers in the water and the water rescue craft.
The infant was taken to hospital as a precaution but is in stable condition.